1. Field of the Invention
The present invention relates to an outboard motor having an air suction device, and more particularly, relates to an outboard motor having a water proof air suction device, wherein water droplets splashed by a screw of the outboard motor is prevented from entering into an air to be introduced into an engine installed in a top cover of the outboard motor.
2. Description of the Prior Art
A conventional outboard motor is normally composed of a main part having therein a driving mechanism and supporting a screw at a lower portion thereof, an engine mounted on an upper portion of the main part and connected to the driving mechanism, and a top cover of synthetic resin covering an outer surface of the engine. Specifically, as shown in FIG. 8, an air suction port 24 is provided at a rearward upper portion of a top cover 20 so as to introduce an atmosphere into an air space 20d formed between the top cover 20 and an engine 18 and to deliver the atmosphere into engine cylinders through air suction pipes 18d arranged in the air space 20d and connected to an air suction box 18c common to the engine cylinders, respectively.
The atmosphere introduced through the air suction port 24 includes water droplets splashed by a screw of the outboard motor. Accordingly, the water droplets are removed in a labyrinth in an air suction room 25 formed between the air suction port 24 and the air space 20d by using a difference in specific gravity of the air and water. Specifically, the atmosphere to be introduced into the engine 18 is commutated in the air suction room 25 and then introduced into the air space 20d formed in the top cover 20 through an opening 22, as shown in the Japanese Patent Application Laid-Open No. 195118/2002, for example.
However, it is difficult to remove fully the water droplets by the conventional simple water droplets removing device, because recently the engine becomes large in power and the suction air quantity becomes large. Accordingly, it has been proposed by the present inventor to use a water proof sheet for preventing the sea water from invading into the engine of the small surface boat, even if the boat is turned over, as shown in the Japanese Patent Application Laid-Open No. 227732/2002, for example.
However, it is difficult to arrange the water proof sheet in the top cover 20 and to discharge suitably the water removed by the water proof sheet to the outside of the top cover 20, because the top cover 20 is formed by thermosetting in the metal mold a thin sheet-like synthetic resin, or a so-called SMC method.
Further, the structure of the top cover becomes complicated so that it is difficult to form by the SMC method, if an air space for the water proof sheet is provided independent of the inside of the top cover, or a passage for discharging the water removed by the water proof sheet to the outside of the top cover is provided.